[9] RFR(XS) 8059780: SPECjvm2008-MPEG performance regressions on x64 platforms

[Igor Veresov]

Looks fine to me.

igor

On Oct 31, 2014, at 2:55 PM, Vladimir Kozlov <vladimir.kozlov at oracle.com> wrote:

> http://cr.openjdk.java.net/~kvn/8059780/webrev/
> https://bugs.openjdk.java.net/browse/JDK-8059780
> 
> We found performance regression (3-5%) on x64 after changes 8052081 [1] were pushed. It is caused by changes in lcm.cpp. Those changes were done because Atom is in-order cpu and some benchmarks on Atom showed benefit from these changes.
> 
> But Atom is not our core platform and the regression is big.
> 
> Backout changes made in lcm.cpp in jdk9 and 8u40 (8052081 was backported to 8u40).
> 
> We have RFEs to improve block's instructions order which may help both platforms:
> 
> https://bugs.openjdk.java.net/browse/JDK-6958833
> https://bugs.openjdk.java.net/browse/JDK-7101232
> 
> Tested with SPECjvm2008-mpegaudio.
> 
> Thanks,
> Vladimir
> 
> [1] https://bugs.openjdk.java.net/browse/JDK-8052081